1. Field of the Invention
This invention relates to an inorganic powder that uses a UV solid light source, in which the chemical formula of the main component is Sr2CaLn2(SiO4)3±δ. When using indium gallium nitride and gallium nitride-based semiconductor allomorphous short wave UV light under excited status, multiple band white light can be obtained.
2. Description of Related Art
In recent years, the manufacturing technology of the solid light source has continuously improved. The illumination efficiency has been increased greatly. Since a solid light source emits a nearly monochrome light wave, and it is advantageously reliable, long-lived, and broadly applicable, it is used in many lighting equipment applications. There is a trend of replacing traditional vacuum light bulbs with solid light sources.
The development of a white light source is a mixture light of multiple colors. The white light observed by human eyes contains a mixture of lights with at least two or more wavelengths. When human eyes are simultaneously excited by red, blue, and green light, or simultaneously excited by light of complementary colors, such as blue and yellow, the light is perceived as white light. This principle can be used to generate a solid light source for white light.
There are main four conventional means of white light solid light source generation:
The first method uses three solid light sources with InGaAlP, GaN, and GaN as materials. It is energized under respective controls, through the solid light sources, to emit red, green, and blue light. Then, a lens is used to mix the emitted light and generate white light.
The second method uses two solid light sources with GaN and GaP as materials. The solid light sources, which are also individually controlled to emit blue and yellow green lights, are energized to generate white light. Although the efficiency of illumination for the above mentioned two methods may reach 20 lm/W, if one of the different color sources' solid light source fails, normal white light cannot be obtained. Further, the positive pressures are different. Thus, there are requirement for many sets of control electric circuits. The cost is high. These are the many disadvantages of practical applications.
The third method was developed in 1996 by Nichia Chemical of Japan. An indium gallium nitride blue solid light source and yellow light-emitting yttrium aluminum garnet fluorescence material are used to form a white light source. Although, at the present time, the efficiency of illumination (as much as 15 lm/W) is lower than that of the previous two methods, only one solid light source chip set is required. The manufacturing cost has been reduced significantly. Furthermore, the formulation and production technology for the fluorescence material is mature, and there are commercial products available.
However, the second and third conventional methods utilize color compensation principle to generate white light. The continuity of spectrum wavelength distribution is not as good as sunlight. After mixture of the color lights, in the visible light spectrum range (400 nm-700 nm), the color is not even. The saturation of color is low. This phenomenon can be ignored by human eyes, and they only perceive white color light. However, a high precision optical detector, such as a video camera or camera, detects the color rendering as low. That is, errors will be caused during reduction. Thus, the white light sources generated by these methods can only be used for simple lighting applications.
The fourth conventional white light generating method was developed by Sumitomo Electric Industries, Ltd of Japan. It uses ZnSe material for the white solid light source. A CdZnSe thin film is first formed on a ZnSe single crystal baseboard. After energizing, the thin film emits blue light. At the same time, a portion of the blue light shines on the baseboard and emits yellow light. Finally, the blue and yellow lights compensate for each other and generate white light. This method utilizes only a solid light source crystal. The operation voltage is only 2.7V, lower than the 3.5V required for a GaN solid light source. Additionally, this method of white light generation does not require fluorescent material. However, the disadvantages are that the efficiency of illumination is only 8 lm/W, and the service life is only 8000 hours.
In addition to the aforesaid white light generation methods by a solid light source, attempts are currently being made to excite, in a controlled manner, Y3Al5O12:Ce fluorescence material. The additives used to replace Al are Ga or Sc. Alternatively, Lu, Tb, and Sm are used to replace Y, but with limited results. However, these fluorescence material radiation light spectrum are normally located in the green-yellow zone of the visible light. That cannot integrate the design of solid light source and the soft white light generated by a white light lamp with an equivalent color temperature of 2800K-3500K
In the current art method announced J. K. Park, the white solid light source uses Ga—N as base, and its cold light properties. (“White Light-emitting Diodes of Ga—N-Based Sr2SiO4:Eu and the Luminescent Properties” J. Electrochem. Solid State Lett., vol 5 {2002} p. H11). The chemical composition used is silicate inorganic powder based on strontium compounds with the chemical formula as Sr2−xEu+2xSiO4. The principle of illumination of inorganic powders is related to the transfer radiation of Eu+2 replacement of Sr+2 ions at the crystal sieve anode nodes. The limited utilization of n-silicate inorganic powder production of standard blue light In—Ga—N allomorphous in white solid light source is that the short wave wavelength used for self excitement is around λ≦420 n, where, for example, λ=395 nm, λ=405 nm, and λ=380 nm are used.
After the aforesaid n-silicate inorganic powder Sr2−xEu+2SiO4 is excited by the UV light, the radiation light spectrum is yellow green, and cold color-adjusted white light can be obtained. Compared to the production equipment of present art using yttrium aluminum garnet fluorescence material, it has a much higher Rendering index. It offers the main advantages of the n-silicate inorganic powder solid light source. However, obtaining these advantages can only be achieved when double portions of inorganic powder mixing agents are used in the solid light source.
In addition to the above-mentioned disadvantage that double portions of inorganic powder mixing agents must be used, the strontium europium-based n-silicate material is very inefficient. When the angles used for the produced white light are between 30° and 120°, the light intensity is J=0.1-0.3 candlelight. At the same time, the heat resistance of this diode should not exceed 80-90° C. That is, when a solid light source is heated to these values, the light brightness is reduced by half. In addition, the temperatures used in the generation process of the inorganic powder is T=1100-1200° C. This is not sufficient to combine the quantum effect of the inorganic powders. During the synthesizing of various known silicate inorganic powder, the vitrification of products easily occurs. This forces the grinding of the vitrified inorganic powder and leads to a lower quantum effect.
For the present art that uses UV chips as solid light source, such as U.S. Pat. No. 6,765,237 “White light-emitting device based on UV solid light source and phosphor blend”, a fluorescent body is provided. The fluorescent body is the combination of two chemical components, to achieve excitation of the white solid light source by UV light. Then, there are the U.S. Pat. Nos. 6,853,131 and 6,522,065 that present a UV solid light source fluorescence body that generates white light. The main component is the A2−2xNa1+xExD2V3O12.